1. Technical Field
The present invention relates to an image and sound output system, to an image and sound data output device, and to a recording medium.
2. Related Art
In recent times, with an image process by a computer improved, a system has been suggested in which an image process having been generally performed by an image display device is performed by the computer, a format of image process data after the image process is converted into a digital format, the image process data is transmitted to an image display device, such as a projector, and an image is displayed by the image display device (for example, see JP-A-2004-69996 (FIG. 1)).
In this system, a serial transmission interface, such as USB or IEEE 1394, is used as a transmission path. When comparing a cable for connecting the serial transmission interface with a general RGB video cable or the like according to the related art, since the cable for connecting the serial transmission interface is thin, it can be easily installed. Therefore, it is expected that the serial transmission interface has been increasingly used as the transmission path.
Meanwhile, image display devices, such as projectors, have been mainly used for a home theater or the like There are cases in which image data obtained by performing an image process using the above-described computer is outputted to the image display device to be displayed thereon. It is considered that a moving picture, such as a video image or a game image, is displayed on an image display device, and a sound according to the moving picture is reproduced and outputted by a data output device, such as the computer.
In this case, the moving picture data is transmitted and received through a serial transmission path between the image display device and the data output device. At this time, the moving picture data is transmitted after being encoded in a format suitable for transmission.
Since the moving picture data is encoded, a decoding process needs to be performed so as to restore an original moving picture in the display device, and both the image display device and the data output device need to perform a buffer process for appropriately transmitting the encoded data at the time of transmission.
At the time of performing the buffer process and the decoding process, and scanning and forming images, a unique process time of the image display device necessarily needs to be ensured. Therefore, in a case in which the data output device transmits the moving picture data to the image display device, and at the same time, a sound attached to the moving picture is reproduced and outputted, reproducing output of the sound data may be earlier than reproducing output of the moving picture, and moving picture output timing and sound output timing, that is, so-called lip-sync does not coincide, which results in applying uncomfortable feeling to viewers.
In order to solve these problems, another system as been suggested in which delay time information based on a unique delay element in a video display device, that is, information of a time necessary until video data is received and then displayed is transmitted to a video and audio output device or an audio adjusting device, such as an amplifier, and a delay buffer of each element is appropriately operated on the basis of the delay time information (for example, see JP-A-2002-344898 (FIG. 4)).
However, according to a technology disclosed in JP-A-2002-344898, a predetermined communication process needs to be performed between devices so as to transmit and receive delay time information, and a communication processing program that becomes a scheme for performing a communication process should be installed in each device. As a result, the development cost and the manufacture cost of each device may increase.